2006 Participants
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Deborah Preston

Debbie Preston is one sophomore currently working with Dr. Blough at the department of Biology. Her research is aimed at getting solutions to issues facing astronauts in space. Her research is based on muscle loading and how it regulates alterations in myosin expression.

The Effects of Microgravity in Skeletal Muscle

"While overloading a muscle results in an increase in fiber size, hypertrophy, decreasing the load on a muscle by removing weight-bearing causes a decrease in fiber size, atrophy.  The phrase "use it or lose it" aptly describes this phenomena.  A dramatic demonstration of unloading occurs during spaceflight where skeletal muscles atrophy very rapidly due to the absence of gravity in spite of the fact that astronauts are subjected to rigorous resistance and endurance training throughout their time in space.  In addition to muscle atrophy, unloading also decreases the muscle content of slow-type I myosin heavy chain (MHC) and oxidative enzymes resulting in a dramatic increase in muscle fatigability.  It is thought that the decreases in muscle endurance associated with these changes may compromise astronaut safety and act to impair the attainment of mission objectives. 

The rat hind limb suspension (HLS) is a terrestrial model of functional atrophy that, like weightlessness, induces a decrease in slow-type I MHC in the slow postural muscles such as the soleus. The factor(s) responsible for these unloading-induced decreases are not known.  The loss of muscle protein in microgravity could be due to a decrease in protein synthesis, an increase in protein degradation, or both.  Using the rat HLS model, analysis of the time course of changes in slow-type I MHC protein and mRNA expression in the soleus muscle revealed that the changes at the mRNA level preceded changes at the protein level.  The mechanism by which HLS may down-regulate the expression of proteins and translational factors are unknown.

Our goal is to shed some light on these questions and gain some insight to the mechanisms which control these changes.  The hope is that we can alter these changes through the use of alternative methods of exercise and/or pharmaceuticals in order to shorten the length of time needed to decrease the effects of microgravity on the endurance and structure of skeletal muscle, and to make space flight safer for astronauts and more efficient for mission objectictives."

View Debbie's Paper